LbuCas13a

LbuCas13a is a CRISPR‑Cas effector protein derived from the bacterium Leptotrichia buccalis. It belongs to the class 2, type VI family of Cas proteins and functions as an RNA‑guided ribonuclease that can both cleave complementary target RNA and, upon activation, indiscriminately degrade nearby RNA molecules in a process termed collateral cleavage. The enzyme forms a ribonucleoprotein complex with a CRISPR RNA (crRNA) that contains a spacer region complementary to the intended target. Binding to a target RNA that satisfies a 5ʹ‑G1G2 motif requirement triggers a conformational change that activates the HEPN (higher eukaryotes and prokaryotes nucleotide-binding) domains responsible for non‑specific RNA cleavage.

LbuCas13a is prized for its high sensitivity and specificity, especially under physiological temperatures around 37 °C. Because of its robust collateral activity, the enzyme is frequently employed in diagnostic platforms, such as SHERLOCK‑style assays, to detect viral or bacterial RNA at very low copy numbers. In addition, engineered variants of LbuCas13a have been used for programmable transcript degradation in mammalian cells, enabling precise control of endogenous RNA levels with minimal off‑target effects. The protein’s amenability to cold‑chain-free storage enhances its suitability for point‑of‑care testing in resource‑limited settings. Current research explores improved crRNA scaffolds and fusion constructs to modulate collateral activity for therapeutic applications. As with other Cas13 enzymes, careful design of guide RNA sequences and stringent biocontainment measures are essential to mitigate unintended cleavage events.